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围垦对崇明东滩湿地全程氨氧化微生物的影响
宋怡轩1, 金 锐1, 张鑫磊1, 张 洁1, 贾仲君2, 张耀鸿1
1.南京信息工程大学气象灾害预报预警与评估协同创新中心/江苏省农业气象重点实验室;2.土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所)
摘要:
全程氨氧化细菌(complete ammonia oxidizers,Comammox)的发现根本改变了学术界对硝化过程的认识,但其地理分异规律及对氮转化过程的贡献仍不清楚。本研究选择长江口崇明东滩不同围垦年限(0、27、51、86 a)稻田表层耕作土壤,采用好氧培养试验测定土壤硝化潜力;通过标靶功能基因amoA实时荧光定量硝化微生物的数量变异特征,包括全程氨氧化细菌(Comammox)、氨氧化细菌(ammonia-oxidizing bacteria,AOB)和氨氧化古菌(ammonia-oxidizing archaea,AOA)。结果表明,与围垦0 a的自然滩涂湿地相比,围垦27、51、86 a的水稻土净硝化速率从N 2.24 mg/(kg?d)分别增加至N 19.3、11.6和11.4 mg/(kg?d),增幅高达5.1 倍~ 8.7倍。AOA的丰度与围垦年限显著正相关。自然滩涂湿地中AOA和AOB的数量分别为0.34×107 copies/g和1.14×107 copies/g,围垦86 a后增幅最高可达27.9倍。自然滩涂湿地中Comammox Clade A和Clade B的amoA基因拷贝数高于围垦稻田土壤,且Comammox Clade A随着围垦年限增加其丰度显著增加。统计分析发现,AOB与土壤硝化速率显著正相关,可能在围垦水稻土氨氧化过程中发挥了重要作用;而Comammox Clade A和Clade B与土壤总有机碳(TOC)、铵含量(NH4+)呈显著负相关关系,可能更适应于营养贫瘠的滩涂自然湿地土壤。
关键词:  围垦  全程氨氧化细菌  氨氧化
DOI:10.13758/j.cnki.tr.2020.06.014
分类号:S154
基金项目:国家自然科学基金项目(41671247, 41103039),江苏省自然科学基金项目( BK20171455) 和江苏省大学生创新创业训练计划项目(201810300094X, 201710300018)资助。
Effect of Reclamation on Abundance of Comammox Microorganism in Chongming Wetland
SONG Yixuan1, JIN Rui1, ZHANG Xinlei1, ZHANG Jie1, JIA Zhongjun2, ZHANG Yaohong1
1.Nanjing University of Information Science and Technology, Collaborative Innovation Center for Forecast and Evaluation of Meteorological Disasters/Jiangsu Provincial Key Laboratory of Agricultural Meteorology;2.State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences
Abstract:
The discovery of comammox broadens our understanding of the nitrification process, but little is known about its natural geographical distribution and its contribution to nitrogen conversion process. In this study, the surface soils of the paddy fields with different reclamation years (0, 27, 51 and 86 a) were selected in the Chongming wetland of the Yangtze River estuary, soil nitrification rates and its influencing factors were determined by aerobic incubation, and the target functional gene amoA was analyzed by real-time fluorescent quantitative PCR to analyze the quantitative variation characteristics of Comammox, ammoxidox bacteria (AOB) and ammonia archaea (AOA). The results showed that the net nitrification rates of paddy soils with 40, 75 and 120 a of reclamation were N 19.26, 11.63 and 11.43 mg/(kg?d), respectively, which were significantly 5.1-8.7 times higher than that of natural tidal wetland (P<0.05). The amoA gene copy number of soil ammonia archaea AOA was between 0.34×107 and 9.95×107 copies/g, which increased significantly with the increase of reclamation year. The amoA gene copy number of soil ammonia bacteria AOB ranged from 1.14×107 to 8.43×107 copies/g, which was significantly positively correlated with soil nitrification rate (r= 0.96*, P<0.05), indicating that AOB might play a dominated role in nitrification process. The Comammox Clade A and Clade B copy number of the soils in the paddy fields (27, 51 and 86 a) were lower than that of tidal flat wetland soil (no reclamation), and Clade A increased significantly with the increase of the reclamation year. Comammox Clade A/Clade B was significantly negatively correlated with soil total organic carbon (TOC) and ammonium content (NH4+), indicating that the ammonia-oxidizing microbes (Clade A, Clade B) are more suitable for nutritional infertility. In summary, Comammox bacteria is widely present in the coastal wetland soils of the Yangtze River estuary, which possibly may play an important role in nitrogen transformation process of tidal flat natural wetlands.
Key words:  Reclamation  Comammox  Ammonia oxidation

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